#pragma once

#include <cstddef>
#include <cstdint>
#include <string>
#include <vector>

// The parts of the network troubleshooting commands (issue #90) that need no network: what was
// asked, the packets to send, and what the answers mean. The sockets are src/services/net_tools.h (a different name on purpose: two headers of one name find themselves).
namespace roro::net {

// --- what was typed

struct PingArgs {
    std::string host;
    int count = 4;   // 1 to 100
    int size = 56;   // bytes of payload, 0 to 1400: with its headers a ping is 28 more
};
// "ping <host> [count] [size]". "" or how to ask.
std::string parsePing(const std::string& args, PingArgs& out);

struct PortArgs {
    std::string host;
    uint16_t port = 0;
};
// "port <host> <port>", or host:port.
std::string parsePort(const std::string& args, PortArgs& out);

struct LookupArgs {
    std::string name, server;  // server: an address, or "" for the one in use
};
std::string parseLookup(const std::string& args, LookupArgs& out);

// --- ICMP: ping and traceroute

uint16_t inetChecksum(const uint8_t* data, size_t len);
// An echo request: 8 bytes of header and `payload` bytes after it. The length written, or 0 if
// it doesn't fit.
size_t buildEcho(uint8_t* out, size_t max, uint16_t id, uint16_t seq, size_t payload);

struct IcmpAnswer {
    enum class Kind { Other, Echo, TimeExceeded, Unreachable } kind = Kind::Other;
    uint16_t id = 0, seq = 0;  // of the echo request it answers
};
// `packet` as a raw socket hands it over: the IP header first. A router's "time exceeded" and
// "unreachable" carry the start of the packet they are about, which is where id and seq come from.
IcmpAnswer parseIcmp(const uint8_t* packet, size_t len);

// What a run of pings came to: "3/4 back, 25% lost, 12/25/41 ms" (the least, the mean, the most).
struct PingStats {
    int sent = 0, back = 0;
    uint32_t minMs = 0, maxMs = 0, sumMs = 0;
    void add(uint32_t ms);
    std::string summary() const;
};

// --- DNS: nslookup

// A query for the IPv4 addresses of `name`. The length written, or 0 if that isn't a name.
size_t buildDnsQuery(uint8_t* out, size_t max, uint16_t id, const std::string& name);

struct DnsAnswer {
    int rcode = 0;           // 0: fine, 3: no such name
    bool truncated = false;  // the answer didn't fit in one packet
    std::vector<uint32_t> addresses;
    std::string alias;       // the last name a CNAME led to, if any
};
// False if it isn't the answer to query `id`, or is cut short.
bool parseDnsAnswer(const uint8_t* message, size_t len, uint16_t id, DnsAnswer& out);

// --- NTP: the clock's offset

constexpr size_t kNtpPacket = 48;
void buildNtpRequest(uint8_t out[kNtpPacket]);
struct NtpAnswer {
    int stratum = 0;        // 1: a reference clock; 2 and up: that many steps from one
    int64_t seconds = 0;    // the server's clock when it answered, UTC since 1970
    uint32_t millis = 0;    // and the part of a second
};
// False if it isn't a server's answer, or says the server has no time to give.
bool parseNtpAnswer(const uint8_t* packet, size_t len, NtpAnswer& out);
// "0.3 s ahead", "12 s behind", "right, to 0.1 s": this clock against the server's, both in ms.
std::string clockOffset(int64_t ownMs, int64_t serverMs);

// --- TLS: who a certificate is for

// The common name out of a certificate's subject or issuer as mbedTLS prints it
// ("C=US, O=Let's Encrypt, CN=R11"): the CN, else the O, else all of it.
std::string certName(const std::string& dn);
// Whole days from one date to another (negative: the second is earlier).
int daysBetween(int y1, int m1, int d1, int y2, int m2, int d2);

// --- netstat

// What listens on a port of this firmware, or "".
const char* portLabel(uint16_t port, bool tcp);

}  // namespace roro::net